This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. This study will attempt to overcome putative specific learning dysfunction in children and adolescents diagnosed with Fragile X syndrome (FXS) using a stimulus equivalence (SE) teaching paradigm. Mathematical performance and brain activation prior to and following SE training will be examined. The efficacy of the intervention will be studied in comparison to a control group of gender, verbal IQ, and age-matched individuals diagnosed with non-specific developmental delay (DD) in order to understand the specificity of mathematical dysfunction exhibited by individuals with FXS. Performance in the targeted skill areas (fraction, pie chart, and decimal conversion) will be compared prior to and following SE training, using functional magnetic resonance imaging (fMRI) and behavioral metrics. To read about other projects ongoing at the Lucas Center, please visit http://rsl.stanford.edu/ (Lucas Annual Report and ISMRM 2011 Abstracts)